Investigation of the influence of processing parameters on the morphology of short fiber reinforced thermoplastics by means of ultrafast scanning calorimetry
Topic(s) : Special Sessions
Co-authors :
Dario KAYLANI (AUSTRIA), Gabriel STADLER (AUSTRIA), Gerald PINTER (AUSTRIA)Abstract :
The increased utilization of short-fiber-reinforced thermoplastics in structural applications necessitates more precise models for predicting the fatigue life of components under intricate loading conditions. Although the impact of certain structure-property relations, such as fiber orientation or notch support effect, on fatigue behavior has been studied in previous research [1, 2], other effects induced by the manufacturing process remain largely unexplored and are presently focus of investigation in this domain. This includes the emergence of local weak spots attributed to weld lines, as well as, in the context of semi-crystalline polymers, different crystalline structures arising from varying process conditions. Thorough exploration of the influence of these parameters on fatigue behavior is imperative for targeted lifetime prediction, performance enhancement and cost reduction in plastic component production. Consequently, the primary objective of this study is to describe cause-effect relationships directly by process-dependent morphological properties that are measurable or predictable, rather than to scrutinize purely phenomenological correlations.
In accordance with various studies [3-5], melt temperature, mold temperature and injection speed were selected as variable process parameters to be investigated. As is well known, thermal history can change the behavior of materials drastically [6]. E.g. upon fast supercooling crystallization can be suppressed to a certain extent. To gain a more profound understanding of the morphology formed during manufacturing, the crystallinity of a technical polymer, in particular a highly fiber reinforced polyamide, was investigated. Measurements were conducted under process-oriented conditions using power compensation twin-type, chip-based fast scanning calorimetry, allowing for cooling rates within the range of a genuine injection molding process as well as heating rates prohibiting cold crystallization and reorganization processes (formation or rearrangement of crystalline structures during slow heating). Thus, as produced morphologic properties can be determined. Subsequently, also the interdependence of microscopic structures, namely fiber orientation and crystallinity, will be further looked into.
In accordance with various studies [3-5], melt temperature, mold temperature and injection speed were selected as variable process parameters to be investigated. As is well known, thermal history can change the behavior of materials drastically [6]. E.g. upon fast supercooling crystallization can be suppressed to a certain extent. To gain a more profound understanding of the morphology formed during manufacturing, the crystallinity of a technical polymer, in particular a highly fiber reinforced polyamide, was investigated. Measurements were conducted under process-oriented conditions using power compensation twin-type, chip-based fast scanning calorimetry, allowing for cooling rates within the range of a genuine injection molding process as well as heating rates prohibiting cold crystallization and reorganization processes (formation or rearrangement of crystalline structures during slow heating). Thus, as produced morphologic properties can be determined. Subsequently, also the interdependence of microscopic structures, namely fiber orientation and crystallinity, will be further looked into.